A Auslander1, M T C Liang2, J Gavin1, E Jo1, J Rocha-Rangel1, J-H Lin3, Y-L Kwoh1, S B Arnaud4. 1. Musculoskeletal Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University, 3801 West Temple Avenue, Pomona, CA, 91765, USA. 2. Musculoskeletal Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University, 3801 West Temple Avenue, Pomona, CA, 91765, USA. mtcliang@cpp.edu. 3. Department of Physical Education, National Pingtung University, Pingtung, Taiwan. 4. Life Science Division, NASA Ames Research Center, Moffett Field, Santa Clara, CA, USA.
Abstract
The rationale was to determine whether body mass index (BMI) is a predictor of bone bending strength and bone mineral density (BMD) in young sedentary women. Results show that BMI is not a predictor of bone bending strength and that young women with low BMI also have low BMD. INTRODUCTION: The purpose of this study was to determine whether body mass index (BMI) is a predictor of tibial or ulnar bending strength and bone mineral density (BMD) in sedentary women. METHODS: Sedentary women (n = 34), age 19-27 years, with low BMI (LBMI < 18.5 kg/m2, n = 16), and normal or high BMI (NHBMI between 18.5 and 29.9 kg/m2, n = 18) participated as study subjects. Study outcomes included tibial and ulnar bending strength (EI in Nm2) using a non-invasive mechanical response tissue analyzer (MRTA); BMD and bone mineral content (BMC) of the whole body (WB), femoral neck (FN), total hip (TH), lumbar spine 1-4 (LS1-4), and ulna; and bone turnover biomarkers. RESULTS: The LBMI group have lower (p < 0.01) body weight [group difference (Δ) = 32.0%], lean mass (LM) (Δ = 23.1%), fat mass (FM) (Δ = 77.2%), and tibial bending strength (Δ = 22.0%), compared to the NHBMI. The LBMI group also have lower (all p < 0.025) BMC in WB (Δ = 19.9%), FN (Δ = 20.1%) and TH (Δ = 19.0%), compared to the NHMBI, not in BMD results. Multivariate regression analysis shows that significant predictors of tibial bending strength are tibia length (adjusted R2 = .341), age (adjusted R2 = .489), ulna BMD (adjusted R2 = .536), and LM (adjusted R2 = .580). BMI was positively correlated with tibial EI (p < 0.05), height, weight, FM, LM, body fat% (all p < 0.01), and BMD of WB, FN, TH, and LS 1-4 (p < 0.05 or < 0.01). CONCLUSIONS: Our results show that BMI is not a significant predictor of tibial or ulnar bending strength in young sedentary women.
The rationale was to determine whether body mass index (BMI) is a predictor of bone bending strength and bone mineral density (BMD) in young sedentary women. Results show that BMI is not a predictor of bone bending strength and that young women with low BMI also have low BMD. INTRODUCTION: The purpose of this study was to determine whether body mass index (BMI) is a predictor of tibial or ulnar bending strength and bone mineral density (BMD) in sedentary women. METHODS: Sedentary women (n = 34), age 19-27 years, with low BMI (LBMI < 18.5 kg/m2, n = 16), and normal or high BMI (NHBMI between 18.5 and 29.9 kg/m2, n = 18) participated as study subjects. Study outcomes included tibial and ulnar bending strength (EI in Nm2) using a non-invasive mechanical response tissue analyzer (MRTA); BMD and bone mineral content (BMC) of the whole body (WB), femoral neck (FN), total hip (TH), lumbar spine 1-4 (LS1-4), and ulna; and bone turnover biomarkers. RESULTS: The LBMI group have lower (p < 0.01) body weight [group difference (Δ) = 32.0%], lean mass (LM) (Δ = 23.1%), fat mass (FM) (Δ = 77.2%), and tibial bending strength (Δ = 22.0%), compared to the NHBMI. The LBMI group also have lower (all p < 0.025) BMC in WB (Δ = 19.9%), FN (Δ = 20.1%) and TH (Δ = 19.0%), compared to the NHMBI, not in BMD results. Multivariate regression analysis shows that significant predictors of tibial bending strength are tibia length (adjusted R2 = .341), age (adjusted R2 = .489), ulna BMD (adjusted R2 = .536), and LM (adjusted R2 = .580). BMI was positively correlated with tibial EI (p < 0.05), height, weight, FM, LM, body fat% (all p < 0.01), and BMD of WB, FN, TH, and LS 1-4 (p < 0.05 or < 0.01). CONCLUSIONS: Our results show that BMI is not a significant predictor of tibial or ulnar bending strength in young sedentary women.